The present invention relates to apparatus for increasing the permeability of wrapping material for rod-shaped smokers' products including tobacco rods, filter rods, filter rod sections and plain or filter tipped cigarettes, cigars and cigarillos. More particularly, the invention relates to apparatus for increasing the permeability of wrappers of such rod-shaped articles in the machine or machines wherein the articles are produced.
It is already known to provide the wrappers of filter cigarettes or like rod-shaped smokers' products with holes or perforations which allow cool atmospheric air to enter the column of tobacco smoke. As a rule, filter tipped smokers' products are perforated in the region of their filter plugs to insure that atmospheric air can enter the column of tobacco smoke irrespective of the length of combusted portion of the tobacco-containing section of the product. The admission of cool atmospheric air into tobacco smoke reduces the harmful effects of smoke because it influences the quantity of nicotine and condensate. It is desirable to regulate the permeability of wrappers of all articles of a given brand in such a way that the permeability is constant or deviates only negligibly from a predetermined value which guarantees maximum beneficial effect of cool atmospheric air upon the column of hot tobacco smoke that flows into the mouth.
Heretofore known proposals to regulate the permeability of wrappers for filter cigarettes or the like include the provision of mechanical perforating devices which puncture the wrappers, for example, during rolling of plain cigarettes and filter plugs to convert such articles into filter cigarettes of unit length or multiple unit length. The perforating devices normally comprise needles whose tips extend into the path of movement of successive wrappers and puncture the wrappers in the region of filter plugs or directly in the filter plugs. The needles are subjected to pronounced wear, especially in a modern high-speed maker which is capable of turning out up to and in excess of 70 articles per second. As the wear upon the needles progresses, the size of each hole increases and the percentage of admitted cool atmospheric air also increases. Therefore, the perforating mechanism must be equipped with adjusting means which compensates for the wear upon the needles. Reference may be had to commonly owned copending patent application Ser. No. 735,166 filed Oct. 26, 1976 by Alfred Hinzmann. Alternatively, the needles must be replaced at frequent intervals which entails lengthy interruptions in operation of the maker.